Related Experiment Video
Updated: May 28, 2026
08:37
Forming, Confining, and Observing Microtubule-Based Active Nematics
Published on: January 13, 2023
Microtubule nucleation by γ-tubulin complexes
Justin M Kollman1, Andreas Merdes, Lionel Mourey
1Howard Hughes Medical Institute and Department of Biochemistry & Biophysics, University of California, San Francisco, San Francisco, California 94143, USA.
Nature Reviews. Molecular Cell Biology
|October 14, 2011
Summary
Microtubule nucleation is guided by the gamma-tubulin ring complex (γTuRC), acting as a template for new microtubule growth. New structural data reveals γTuRC organization and a novel regulatory mechanism involving GCP3.
Area of Science:
- Cell Biology
- Structural Biology
- Biochemistry
Background:
- Microtubule nucleation, essential for cell division and structure, is orchestrated by the gamma-tubulin ring complex (γTuRC).
- The γTuRC's role as a microtubule template has been hypothesized but lacked direct structural evidence.
- Understanding γTuRC regulation is crucial for comprehending microtubule dynamics and cellular organization.
Purpose of the Study:
- To elucidate the structural basis of γTuRC function and regulation.
- To refine models of γTuRC organization and protein interactions.
- To investigate novel mechanisms controlling γTuRC activity and localization.
Main Methods:
- Crystallographic analysis of γ-tubulin complex protein 4 (GCP4), a non-γ-tubulin component.
- Integration of structural data with existing knowledge of γTuRC components.
- Experimental studies on γTuRC localization and its correlation with activation.
Main Results:
- The first crystal structure of GCP4 provides insights into γTuRC protein relationships and organization.
- A refined model of γTuRC assembly and function has been proposed.
- Conformational modulation of GCP3 emerged as a potential regulatory mechanism for γTuRC activity.
- γTuRC attachment to cellular sites correlates with its activation.
Conclusions:
- Structural studies confirm the γTuRC's function as a microtubule nucleation template.
- New structural insights refine our understanding of γTuRC organization and regulation.
- GCP3-mediated conformational changes represent a novel pathway for controlling microtubule nucleation.
- Cellular localization is directly linked to γTuRC activation, highlighting spatial regulation.
Related Concept Videos
01:23Microtubule Formation
Microtubules are dynamic structures that undergo continuous assembly and disassembly. They originate from specialized multi-protein complexes known as microtubule organizing centers or MTOCs. Within the MTOC, the point of origin of the microtubule is known as the minus end, while the end radiating outward is the plus end. Microtubules serve two primary functions — the organization of spindle complexes to separate sister chromatids during mitotic or meiotic cell division and the formation of...
02:50Spindle Assembly
Spindle assembly occurs through three, often coexisting, pathways – the centrosome-mediated pathway, the chromatin-mediated pathway, and the microtubule-mediated pathway – collectively contributing to form a robust spindle apparatus.
In most cells, centrosomes are the primary microtubule nucleation centers. In the centrosome-mediated pathway, the G2-prophase transition triggers centrosome maturation and increased microtubule nucleation. Progressive nucleation results in a microtubule array...
In most cells, centrosomes are the primary microtubule nucleation centers. In the centrosome-mediated pathway, the G2-prophase transition triggers centrosome maturation and increased microtubule nucleation. Progressive nucleation results in a microtubule array...
02:17Microtubule Instability
Microtubules are hollow cylindrical filaments having a diameter of approximately 25 nm and a length that varies from 200 nm to 25 μm. GTP-bound tubulin subunits form αβ-heterodimers for microtubule assembly. These core building blocks interact longitudinally, polymerizing into protofilaments. The protofilaments then interact with one another through lateral bonding forces to form stable cylindrical microtubules. These cylindrical filaments are dynamic as they undergo repeated assembly and...
02:17Microtubule Instability
Microtubules are hollow cylindrical filaments having a diameter of approximately 25 nm and a length that varies from 200 nm to 25 μm. GTP-bound tubulin subunits form αβ-heterodimers for microtubule assembly. These core building blocks interact longitudinally, polymerizing into protofilaments. The protofilaments then interact with one another through lateral bonding forces to form stable cylindrical microtubules. These cylindrical filaments are dynamic as they undergo repeated assembly and...
01:32Assembly of Complex Microtubule Structures
Complex microtubule structures are present in resting cells and in dividing cells. In resting cells, they are responsible for maintaining the cellular architecture, tracks for intracellular transport, positioning of organelles, assembly of cilia and flagella. They mediate the bipolar spindle assembly for chromosomal segregation and positioning of the cell division plate in dividing cells. The formation of microtubule complex structures depends on the cell type, cell stage, and cell function.
01:39Anaphase A and B
Microtubules form through the end-to-end polymerization of tubulin heterodimers. Kinetochore microtubules originate from the spindle poles, and their plus-ends connect with the kinetochores on sister-chromatids. Ndc80 protein complexes, present on the kinetochore, form low-affinity links with the plus end of these kinetochore microtubules.
Plus-end depolymerization releases tubulin heterodimers from the terminal region of the microtubule. As tubulin subunits are lost, the Ndc80 complexes detach...
Plus-end depolymerization releases tubulin heterodimers from the terminal region of the microtubule. As tubulin subunits are lost, the Ndc80 complexes detach...